Method of asphalt manufacture



Patented Apr. 7, 1942 t;;.uu;irso STAT-ES" PATE OFFICE METHOD OF ASPHALT MANUFACTURE Joseph C. Roediger, Brooklyn, Y., assignor to StandardfOil Development Company, a corpo ration of Delaware No Drawing.

Application October 10, 1939, Serial No. 298,799 I '7 claims; (crue -273) This invention relates to'improvements in the manufacture of bituminous materials such as are used as bonding agents for mineral aggregates in road construction. It relates particularly to the preparation of bituminous bonding materials from petroleum oils that have been subjected to generally known as or stone, the heat under normal summer conditions will cause the asphalt to softenalmost to the point of being fluid. This will ooze out of the joint onto the blocks, rendering themstickyh An asphalt with low susceptibility will not soften to any such degree under the'same conditions and although expansion will take place, the bitumen will remain in a more or=less solid, nonsticky condition, In an asphalt macadam road,

other conditions being equal, a highly susceptible asphalt tends to lower road stability and cause displacement under theaction' of heavy trafilc in hot weather, because the asphalt will soften to a greater degree and hence, lose more of its bonding power than one of low susceptibility.

Cracking coil tars if reduced by vacuum flashing to a high softening point bottoms which is then blended with a'low viscosity cracking coil tar produced from gas oil result in asphalts having slightly better susceptibility characteristics than that of a gas oil tar reduced to equal penetration or softening point. However, the blended asphalt generally has a high ductility, e. g. 100+ at 77 F., for grades having penetrations at 77 F. in the range of 200.

If cracking coil tar, reduced to a relatively high softening point in a similar manner as pointed out above; is blended with relatively low viscosity tars produced from the cracking or vis-' cosity breaking of a reduced crude, an asphalt results with susceptibility characteristics, both at normal temperatures (softening point/penetration index) and at sub-normal temperatures (penetration 77/32 F. ratio), superior to straight reduced Mexican asphalt of equal penetration. The index and ratio are shown numerically in the following tables. Basic figures used ior desenting products having a low consistency-temperature'coemcient, while'those from petroleum tar were selected as the other extreme, that is, as 0 on the scale, representing asphalts with a high consistency-temperature coeflicient. In this discussion, petroleum tar is to be considered as the residue from the cracking of virgin gas oil under high temperature and pressure.

TABLE 1 Numerical magnitude of softening tration index point -pene- Range-of values for softening point-penetration index; paving range 30-90 penetration at 25 C.

A sphalts" Mexican 100 Venezuelan -88 Colombian. 67-77 Heavy Smac 82-94 West Texas 59-62 Hcaldton 70-76 Mid-Continent 59-65 Van Zan t 68-75 California (Kern River) 14-27 East Venezuelan l027 Petroleum tar from cracked gas oil 0 *Straiglit reduced asphalts.

Penetration range, penetration at ..n C. per grains per 5 seconds.

TABLE 2 Numerical magnitude of the susceptibility factor at subnormal temperatures Susceptibility factor== penetration at 25 C. per 100 grams per 5 seconds) penetration at 0 C. per 200 grams per 60 seconds Range of susceptibility factor values. paving range 30-90 penctration at 25 C.

Asphalt? Mexican Venezuelan.

Colombian. M. .l'l envy Smack-over.

California liorriitivet East Venezuelan V Petroleum tar from cracked gasml point reduced tar is blended with'a suitable combination of both relatively low viscosity gas oil tar and low viscosity reduced crude tar. The proportions of each ingredient can be so regulated that the desirable susceptibility characteristics of a straight reduced asphalt produced from an uncracked crude oil and high ductility may be produced within the range of properties resulting when either low consistency tar is used alone in preparing the blend. The susceptibility characteristics of these blended asphalts can be regulated so they are equal to or slightly. better than those of straight reduced asphalts, such as those produced from Colombia or Mexican crude oils. In the following table are disclosed the eilects' of blending a high melting point cracking coil tar with gas oil tars and with petroleum tars such as are obtained by the cracking of crude oil or reduced crude oil. The effects of the various constitu'ents entering into a combination of these three ingredients and also the softening points of the ingredients are illustrated in the followin table:

I. Blend (percent by weight):

250 softening point tar, F., A.S.T.M 48.0 33.0 40. 5 Gas oiltaril 52.0 26.0 Visbreaker tar from crude oil" 67. 33. Il. Inspections on blend:

Softening point, F., A.B.T.M 109 123 117 Penetration 77 1'., A.S.T.M 93 100 87 Penetration 32 F., A.S.T.M. 28 48 33 Ductility 77 F A.S.T.M 26 90-95 Ill. Susceptibility:

Softening point/penetration 77 index. 5 126 75 Penetration 77/penetration 32 F 3. 32 2. 1 2. 64

' Gas oil tar Il=l2l (moi/122 F. "Visbreaker tar=l2 {moi/122 F.

I. Blend r cent by weight):

350so tenin point tar, "F A. S. T. M.. 25 Gas ciltar 32.5 Visbreaker tar horn crude oil" 37. 5 II. Inspections on blend:

Softening point, R, A. S. T. M 108 v 125 114 Penetration 77 it, A. S. T. M 114 100 100 Penetration 32 F., A. S. T. M- 24 49 37 Ductility 77 F., A. S. T. M 100+ 15 100+ III. Susceptibility:

Softening point/penetration 77 index. 14 136 70 Penetration 77 lpenetration 32 F 4. 76 Z 0 2. 7

m oil tar #2-599 [moi/122 F. "Visbreaker tar-1512 [moi/122 F.

The 250 F.- and 350 F. softening point tars were produced by vacuum reducing in a pipe still a mixture of gas oil tar and reduced crude tar. This is for illustration only, as the high softening point tars may be prepared from gas oil tars or reduced crude tars alone. It should be noted that the asphalts produced by the blending of the aavacu Susceptibility of normal crude asphalts Penetration 77] Softening point] penetration index ggg Mexican (Pounce) u'udc 3. 3 Colombian crude 68 4. 4 Reduced gas oil tar"...- 0 l2. 0

It is obvious how the proportions of the two low viscosity tars in the final blend can be regulated to produce asphalts having different susceptibility characteristics and diflferent ductilities within the range of the properties resulting when either tar is used alone in a blend.

By a reduction of the relatively low viscosity tars to suitable flash points and volatility charlow viscosity cracking coil tar produced from gas three tars have susceptibility characteristics better than that prepared by straight reduction from Colombia crude and considerably better over the asphalt attainable by the reduction of the reduced gas oil tars alone.

oil and low viscosity tars produced from the cracking of crude petroleum oil.

2. A process of producing a bituminous bonding agent which comprises blending a high softening point cracking coil tar with a relatively low viscosity cracking coil tar produced from gas oil and low viscosity tars produced from the cracking of reduced crude petroleum oil.

3. A process of producing an asphalt from cracked source materials which will have improved susceptibility characteristics over those capable of being produced by straight reduction of the gas oil or of reduced crude tars alone. which comprises blending a cracking coil tar of at least F. softening point with a relatively low viscosity cracking coil tar produced from gas oil and low viscosity tars produced from the cracking of reduced crude petroleum oil.

4. A process of producing an asphalt from cracked source materials which will have improved susceptibility characteristics over those capable of being produced by thestraight reduction of gas oil or reduced crude tar oil alone, which comprises blending a minor proportion of a cracking coil tar having a softening point of at least 185 F. with a major proportion of cracking coil tars produced from gas oil and low viscosity tars produced from the cracking of crude petroleum oils.

5. A process of producing an asphalt from cracked source materials which will have improved susceptibility characteristics, whichcom- F. of at least 121 to 599 seconds and a tar pro-- duced from petroleum oils having a viscosity 1512 seconds furol at 122 F.

' JOSEPH C. ROEDIGER. 

